Clusters with multiple points of entry
This scenario gives you the ability to provide the highest availability to the users with no single point of failure in the
whole cluster setup.
In this scenario, multiple Cluster Services provide authentication and load balancing services and access to multiple servers.
The multiple Cluster Services setup has multiple entry points. A Domain Name Server (DNS) acts as a single point-of- entry
for users and performs round-robin distribution of incoming requests to the configured Cluster Services. The Cluster Services
are responsible for returning the correct address of the least busy server to which the users can connect.
Figure 3: Multiple points of entry setup overview
In above scenario, we have two levels of load balancing. First, the DNS performs load balancing (simple round-robin) regardless
of the load on the Servers, and then the Cluster Services perform load balancing on the actual load on each server.
The number and location of the Cluster Services need not match the number and location of Servers. Both components can be
installed on different machines.
Configuring a cluster with multiple points of entry
Follow the steps below to configure a cluster with multiple points of entry.
| 1. | During the installation, provide the IP address of the designated DNS that will act as a network point of entry. If you missed this point during the installation, you can either redo the installation procedure or edit the HTML pages. |
| 2. | Add multiple cluster service entries in Host Access Manager. |
| 3. | Add multiple Server entries in Host Access Manager. |
Notes
For the initial load balancing, you can use either a DNS server or any other IP load balancing device or solution (such as
Microsoft Windows Load Balancing Service - WLBS). Note that in all cases, the DNS (or other device) needs to have the following
mappings of IP addresses on the external interface:
| • | One IP address (or name) to act as the single virtual point of entry. Users accessing this IP (or name) will be subject to round-robin load balancing. |
| • | One IP address (or name) per Server (machine running one set of emulation services). Each of these IP addresses will be mapped directly to one of the Server addresses. These IP's (or DNS names) must match the configuration made in the cluster configuration for the server Public name or IP address. |